/**
 * Copyright (c) 2005-2012 springside.org.cn
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 */
package com.fand.utils;

import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;

import org.apache.commons.lang3.StringUtils;
import org.apache.commons.lang3.Validate;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.util.Assert;

/**
 * 反射工具类. 提供调用getter/setter方法, 访问私有变量, 调用私有方法, 获取泛型类型Class, 被AOP过的真实类等工具函数.
 * 
 * @author yaoHT
 */
public class Reflections {
	private static final String CGLIB_CLASS_SEPARATOR = "$$";
	
	private static final String GETTER_PREFIX = "get";
	
	private static Logger logger = LoggerFactory.getLogger(Reflections.class);
	
	private static final String SETTER_PREFIX = "set";
	
	/**
	 * 循环向上转型, 获取对象的DeclaredField, 并强制设置为可访问. 如向上转型到Object仍无法找到, 返回null.
	 */
	public static Field getAccessibleField(final Object obj, final String fieldName) {
		Validate.notNull(obj, "object can't be null");
		Validate.notBlank(fieldName, "fieldName can't be blank");
		for (Class<?> superClass = obj.getClass(); superClass != Object.class; superClass = superClass
		        .getSuperclass()) {
			try {
				final Field field = superClass.getDeclaredField(fieldName);
				Reflections.makeAccessible(field);
				return field;
			} catch (final NoSuchFieldException e) {// NOSONAR
				// Field不在当前类定义,继续向上转型
			}
		}
		return null;
	}
	
	/**
	 * 循环向上转型, 获取对象的DeclaredMethod,并强制设置为可访问. 如向上转型到Object仍无法找到, 返回null.
	 * 匹配函数名+参数类型。 用于方法需要被多次调用的情况. 先使用本函数先取得Method,然后调用Method.invoke(Object obj,
	 * Object... args)
	 */
	public static Method getAccessibleMethod(final Object obj, final String methodName,
	        final Class<?>... parameterTypes) {
		Validate.notNull(obj, "object can't be null");
		Validate.notBlank(methodName, "methodName can't be blank");
		
		for (Class<?> searchType = obj.getClass(); searchType != Object.class; searchType = searchType
		        .getSuperclass()) {
			try {
				final Method method = searchType.getDeclaredMethod(methodName, parameterTypes);
				Reflections.makeAccessible(method);
				return method;
			} catch (final NoSuchMethodException e) {
				// Method不在当前类定义,继续向上转型
			}
		}
		return null;
	}
	
	/**
	 * 循环向上转型, 获取对象的DeclaredMethod,并强制设置为可访问. 如向上转型到Object仍无法找到, 返回null. 只匹配函数名。
	 * 用于方法需要被多次调用的情况. 先使用本函数先取得Method,然后调用Method.invoke(Object obj, Object...
	 * args)
	 */
	public static Method getAccessibleMethodByName(final Object obj, final String methodName) {
		Validate.notNull(obj, "object can't be null");
		Validate.notBlank(methodName, "methodName can't be blank");
		
		for (Class<?> searchType = obj.getClass(); searchType != Object.class; searchType = searchType
		        .getSuperclass()) {
			final Method[] methods = searchType.getDeclaredMethods();
			for (final Method method : methods) {
				if (method.getName().equals(methodName)) {
					Reflections.makeAccessible(method);
					return method;
				}
			}
		}
		return null;
	}
	
	/**
	 * 通过反射, 获得Class定义中声明的父类的泛型参数的类型. 如无法找到, 返回Object.class. 如public UserDao
	 * extends HibernateDao<User,Long>
	 * 
	 * @param clazz
	 *            clazz The class to introspect
	 * @param index
	 *            the Index of the generic ddeclaration,start from 0.
	 * @return the index generic declaration, or Object.class if cannot be
	 *         determined
	 */
	public static Class<?> getClassGenricType(final Class<?> clazz, final int index) {
		
		final Type genType = clazz.getGenericSuperclass();
		
		if (!(genType instanceof ParameterizedType)) {
			Reflections.logger.warn(clazz.getSimpleName() + "'s superclass not ParameterizedType");
			return Object.class;
		}
		
		final Type[] params = ((ParameterizedType) genType).getActualTypeArguments();
		
		if ((index >= params.length) || (index < 0)) {
			Reflections.logger.warn("Index: " + index + ", Size of " + clazz.getSimpleName()
			        + "'s Parameterized Type: " + params.length);
			return Object.class;
		}
		if (!(params[index] instanceof Class)) {
			Reflections.logger.warn(clazz.getSimpleName()
			        + " not set the actual class on superclass generic parameter");
			return Object.class;
		}
		
		return (Class<?>) params[index];
	}
	
	/**
	 * 通过反射, 获得Class定义中声明的泛型参数的类型, 注意泛型必须定义在父类处 如无法找到, 返回Object.class. eg.
	 * public UserDao extends HibernateDao<User>
	 * 
	 * @param clazz
	 *            The class to introspect
	 * @return the first generic declaration, or Object.class if cannot be
	 *         determined
	 */
	@SuppressWarnings("unchecked")
	public static <T> Class<T> getClassGenricType(final Class<T> clazz) {
		return (Class<T>) Reflections.getClassGenricType(clazz, 0);
	}
	
	/**
	 * 直接读取对象属性值, 无视private/protected修饰符, 不经过getter函数.
	 */
	public static Object getFieldValue(final Object obj, final String fieldName) {
		final Field field = Reflections.getAccessibleField(obj, fieldName);
		
		if (field == null) { throw new IllegalArgumentException("Could not find field [" + fieldName
		        + "] on target [" + obj + "]"); }
		
		Object result = null;
		try {
			result = field.get(obj);
		} catch (final IllegalAccessException e) {
			Reflections.logger.error("不可能抛出的异常{}", e.getMessage());
		}
		return result;
	}
	
	public static Class<?> getUserClass(final Object instance) {
		Assert.notNull(instance, "Instance must not be null");
		final Class<?> clazz = instance.getClass();
		if ((clazz != null) && clazz.getName().contains(Reflections.CGLIB_CLASS_SEPARATOR)) {
			final Class<?> superClass = clazz.getSuperclass();
			if ((superClass != null) && !Object.class.equals(superClass)) { return superClass; }
		}
		return clazz;
		
	}
	
	/**
	 * 调用Getter方法.
	 */
	public static Object invokeGetter(final Object obj, final String propertyName) {
		final String getterMethodName = Reflections.GETTER_PREFIX + StringUtils.capitalize(propertyName);
		return Reflections.invokeMethod(obj, getterMethodName, new Class[] {}, new Object[] {});
	}
	
	/**
	 * 直接调用对象方法, 无视private/protected修饰符.
	 * 用于一次性调用的情况，否则应使用getAccessibleMethod()函数获得Method后反复调用. 同时匹配方法名+参数类型，
	 */
	public static Object invokeMethod(final Object obj, final String methodName, final Class<?>[] parameterTypes,
	        final Object[] args) {
		final Method method = Reflections.getAccessibleMethod(obj, methodName, parameterTypes);
		if (method == null) { throw new IllegalArgumentException("Could not find method [" + methodName
		        + "] on target [" + obj + "]"); }
		
		try {
			return method.invoke(obj, args);
		} catch (final Exception e) {
			throw new RuntimeException(e);
		}
	}
	
	/**
	 * 直接调用对象方法, 无视private/protected修饰符，
	 * 用于一次性调用的情况，否则应使用getAccessibleMethodByName()函数获得Method后反复调用.
	 * 只匹配函数名，如果有多个同名函数调用第一个。
	 */
	public static Object invokeMethodByName(final Object obj, final String methodName, final Object[] args) {
		final Method method = Reflections.getAccessibleMethodByName(obj, methodName);
		if (method == null) { throw new IllegalArgumentException("Could not find method [" + methodName
		        + "] on target [" + obj + "]"); }
		
		try {
			return method.invoke(obj, args);
		} catch (final Exception e) {
			throw new RuntimeException(e);
		}
	}
	
	/**
	 * 调用Setter方法, 仅匹配方法名。
	 */
	public static void invokeSetter(final Object obj, final String propertyName, final Object value) {
		final String setterMethodName = Reflections.SETTER_PREFIX + StringUtils.capitalize(propertyName);
		Reflections.invokeMethodByName(obj, setterMethodName, new Object[] { value });
	}
	
	/**
	 * 改变private/protected的成员变量为public，尽量不调用实际改动的语句，避免JDK的SecurityManager抱怨。
	 */
	public static void makeAccessible(final Field field) {
		if ((!Modifier.isPublic(field.getModifiers())
		        || !Modifier.isPublic(field.getDeclaringClass().getModifiers()) || Modifier.isFinal(field
		        .getModifiers())) && !field.isAccessible()) {
			field.setAccessible(true);
		}
	}
	
	/**
	 * 改变private/protected的方法为public，尽量不调用实际改动的语句，避免JDK的SecurityManager抱怨。
	 */
	public static void makeAccessible(final Method method) {
		if ((!Modifier.isPublic(method.getModifiers()) || !Modifier.isPublic(method.getDeclaringClass()
		        .getModifiers())) && !method.isAccessible()) {
			method.setAccessible(true);
		}
	}
	
	/**
	 * 直接设置对象属性值, 无视private/protected修饰符, 不经过setter函数.
	 */
	public static void setFieldValue(final Object obj, final String fieldName, final Object value) {
		final Field field = Reflections.getAccessibleField(obj, fieldName);
		
		if (field == null) { throw new IllegalArgumentException("Could not find field [" + fieldName
		        + "] on target [" + obj + "]"); }
		
		try {
			field.set(obj, value);
		} catch (final IllegalAccessException e) {
			Reflections.logger.error("不可能抛出的异常:{}", e.getMessage());
		}
	}
	
}
